SK On Just Pushed Solid-State EV Batteries Closer to Reality

• South Korean battery giant SK On has started the trial production of all-solid-state batteries.
• The company said it was using a unique process to make the electrodes reliably on an automated production line.
• U.S.-based Solid Power and SK On have been working on solid-state batteries for more than a year.

Solid-state batteries for electric vehicles are slowly coming out of the lab and inching towards reality. Korean EV battery giant SK On, a supplier to Hyundai, Kia, Ford and Nissan, among others, said on Monday that it had opened its first pilot production line for solid-state batteries in the city of Daejeon, with plans for commercialization by the end of the decade.

These next-generation batteries swap the liquid electrolyte—the material which facilitates the movement of ions during charge and discharge cycles—with a solid electrolyte. At least on paper, the benefits include substantially better resistance to fire, vast improvements in energy density leading to longer driving range, and improved fast charging speeds.

SK On Lithium Ion Battery Pouch Cell

Photo by: SK On

For more than a decade, scholars and industry experts have referred to solid-state batteries as the “holy grail” of battery technology in several published scientific papers. But industry experts also warned that the technology was too theoretical, and scaling up is a massive challenge. Still, automakers and battery companies have continued their research and development and are getting closer to commercialization.

SK On’s facility will build prototype cells for assessment and validation before they’re greenlit for commercial production. The company is collaborating with Colorado-based battery start-up Solid Power to develop these cells, which the company claims have an energy density of 800 watt hours per liter, which is more than the average 400-500 Wh/L energy density of nickel-based lithium ion batteries on the cell level.

The company claims that over time, its all-solid-state cells could reach an energy density of 1,000 Wh/L. It’s also claiming that its 50,000 square foot pilot production plant will use what’s called a “warm isostatic press-free” technology, which applies uniform pressure on electrodes to improve energy density and performance.

SK On’s U.S. EV battery plant in Georgia.

Photo by: SK On

The most common materials for solid electrolytes include sulfides, polymers, ceramic oxides or some sort of hybrid or composite materials. SK On said its pilot production line will begin producing sulfide-based all-solid-state batteries and some lines will also make lithium-metal batteries, which replace the graphite anode with one made from pure lithium metal.

But SK On admitted that building these cells was far from easy. It said its patented technology requires “cell sealing,” which is a challenging process to automate on a continuous production line, and that’s something the company will hope to iron out during the pilot phase.

To address this issue, the company claims to have tweaked how battery materials are mixed and pressed to cut down resistance, which keeps cells cooler and more efficient. It also improved how electrodes (anode and cathode) bond with solid electrolytes, making the ions flow smoothly for longer-lasting, more stable batteries.

The all-solid-state batteries will enter commercial production by 2029, a full year ahead of schedule, according to the company. Notably, SK On is also working to bring low-cost lithium-iron phosphate (LFP) battery production to the U.S. for battery energy storage systems. Plus, its BlueOval SK joint venture with Ford started manufacturing nickel-manganese-cobalt (NMC) batteries at a $5.8 billion plant in Glendale, Kentucky, in August for the F-150 Lightning and the E-Transit van.

The solid-state era may be arriving sooner than we think. 

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